diff --git a/buildSrc/build.gradle b/buildSrc/build.gradle
index f5f565fcc8fe5..c18b01261f31f 100644
--- a/buildSrc/build.gradle
+++ b/buildSrc/build.gradle
@@ -133,6 +133,14 @@ dependencies {
   integTestImplementation('org.spockframework:spock-core:2.4-M6-groovy-4.0') {
     exclude module: "groovy"
   }
+  // Integration with JUnit 4 features for Spock 2+ (which internally uses JUnit Platform -
+  // part of JUnit 5) - https://spockframework.org/spock/docs/2.4-M6/modules.html
+  integTestImplementation('org.spockframework:spock-junit4:2.4-M6-groovy-4.0') {
+    exclude module: "groovy"
+  }
+  integTestImplementation(platform("org.junit:junit-bom:${props.getProperty('junit5')}"))
+  integTestRuntimeOnly("org.junit.platform:junit-platform-launcher")
+  integTestRuntimeOnly("org.junit.vintage:junit-vintage-engine")
 }
 
 configurations.all {
@@ -253,6 +261,7 @@ if (project != rootProject) {
   }
 
   tasks.register("integTest", Test) {
+    useJUnitPlatform()
     inputs.dir(file("src/testKit")).withPropertyName("testkit dir").withPathSensitivity(PathSensitivity.RELATIVE)
     systemProperty 'test.version_under_test', version
     onlyIf { org.opensearch.gradle.info.BuildParams.inFipsJvm == false }
diff --git a/buildSrc/src/integTest/groovy/org/opensearch/gradle/DistributionDownloadPluginFuncTest.groovy b/buildSrc/src/integTest/groovy/org/opensearch/gradle/DistributionDownloadPluginFuncTest.groovy
index d49c85f0f0e17..634cd208a1df2 100644
--- a/buildSrc/src/integTest/groovy/org/opensearch/gradle/DistributionDownloadPluginFuncTest.groovy
+++ b/buildSrc/src/integTest/groovy/org/opensearch/gradle/DistributionDownloadPluginFuncTest.groovy
@@ -56,8 +56,8 @@ class DistributionDownloadPluginFuncTest extends AbstractGradleFuncTest {
         where:
         version                              | platform                                   | distType
         VersionProperties.getOpenSearch()    | OpenSearchDistribution.Platform.LINUX      | "current"
-        "8.1.0-SNAPSHOT"                     | OpenSearchDistribution.Platform.LINUX   | "bwc"
-        "7.0.0"                              | OpenSearchDistribution.Platform.WINDOWS | "released"
+        "2.19.0-SNAPSHOT"                    | OpenSearchDistribution.Platform.LINUX   | "bwc"
+        "3.3.0"                              | OpenSearchDistribution.Platform.WINDOWS | "released"
     }
 
 
@@ -72,7 +72,8 @@ class DistributionDownloadPluginFuncTest extends AbstractGradleFuncTest {
         """
 
         when:
-        def runner = gradleRunner('clean', 'setupDistro', '-i')
+        def customGradleUserHome = testProjectDir.newFolder().absolutePath;
+        def runner = gradleRunner('clean', 'setupDistro', '-i', '-g', customGradleUserHome)
         def result = withMockedDistributionDownload(version, platform, runner) {
             // initial run
             build()
@@ -82,7 +83,8 @@ class DistributionDownloadPluginFuncTest extends AbstractGradleFuncTest {
 
         then:
         result.task(":setupDistro").outcome == TaskOutcome.SUCCESS
-        assertOutputContains(result.output, "Skipping ${SymbolicLinkPreservingUntarTransform.class.simpleName}")
+        result.output.count("Unpacking opensearch-${version}-linux-x64.tar.gz " +
+            "using SymbolicLinkPreservingUntarTransform.") == 0
     }
 
     def "transforms are reused across projects"() {
@@ -91,6 +93,7 @@ class DistributionDownloadPluginFuncTest extends AbstractGradleFuncTest {
         def platform = OpenSearchDistribution.Platform.LINUX
 
         3.times {
+            testProjectDir.newFolder("sub-$it")
             settingsFile << """
                 include ':sub-$it'
             """
diff --git a/buildSrc/src/integTest/groovy/org/opensearch/gradle/JdkDownloadPluginFuncTest.groovy b/buildSrc/src/integTest/groovy/org/opensearch/gradle/JdkDownloadPluginFuncTest.groovy
index 160e7805b3648..c070dbf7cd535 100644
--- a/buildSrc/src/integTest/groovy/org/opensearch/gradle/JdkDownloadPluginFuncTest.groovy
+++ b/buildSrc/src/integTest/groovy/org/opensearch/gradle/JdkDownloadPluginFuncTest.groovy
@@ -108,6 +108,7 @@ class JdkDownloadPluginFuncTest extends AbstractGradleFuncTest {
         def mockRepoUrl = urlPath(jdkVendor, jdkVersion, platform)
         def mockedContent = filebytes(jdkVendor, platform)
         3.times {
+            testProjectDir.newFolder("sub-$it")
             settingsFile << """
                 include ':sub-$it'
             """
@@ -193,7 +194,7 @@ class JdkDownloadPluginFuncTest extends AbstractGradleFuncTest {
         }
 
         then:
-        assertOutputContains(result.output, "Skipping $transformType")
+        result.output.count("Unpacking ${platform}-12.0.2-x64.tar.gz using ${transformType}.") == 0
 
         where:
         platform  | transformType
@@ -246,6 +247,7 @@ class JdkDownloadPluginFuncTest extends AbstractGradleFuncTest {
                 p.repositories.all { repo ->
                     if(repo.name == "jdk_repo_${jdkVendor}_${jdkVersion}") {
                       repo.setUrl('${server.baseUrl()}')
+                      repo.setAllowInsecureProtocol(true)
                     }
                 }
            }"""
diff --git a/buildSrc/src/integTest/groovy/org/opensearch/gradle/internal/InternalDistributionArchiveSetupPluginFuncTest.groovy b/buildSrc/src/integTest/groovy/org/opensearch/gradle/internal/InternalDistributionArchiveSetupPluginFuncTest.groovy
index fa36bd36ed031..9d853cebfc4d1 100644
--- a/buildSrc/src/integTest/groovy/org/opensearch/gradle/internal/InternalDistributionArchiveSetupPluginFuncTest.groovy
+++ b/buildSrc/src/integTest/groovy/org/opensearch/gradle/internal/InternalDistributionArchiveSetupPluginFuncTest.groovy
@@ -98,6 +98,9 @@ class InternalDistributionArchiveSetupPluginFuncTest extends AbstractGradleFuncT
         given:
         file('someFile.txt') << "some content"
 
+        testProjectDir.newFolder("consumer")
+        testProjectDir.newFolder("producer-tar")
+
         settingsFile << """
             include ':consumer'
             include ':producer-tar'
diff --git a/buildSrc/src/integTest/groovy/org/opensearch/gradle/internal/InternalDistributionDownloadPluginFuncTest.groovy b/buildSrc/src/integTest/groovy/org/opensearch/gradle/internal/InternalDistributionDownloadPluginFuncTest.groovy
index 46143687b83a7..70c3df59f84f8 100644
--- a/buildSrc/src/integTest/groovy/org/opensearch/gradle/internal/InternalDistributionDownloadPluginFuncTest.groovy
+++ b/buildSrc/src/integTest/groovy/org/opensearch/gradle/internal/InternalDistributionDownloadPluginFuncTest.groovy
@@ -122,6 +122,8 @@ class InternalDistributionDownloadPluginFuncTest extends AbstractGradleFuncTest
         internalBuild()
         bwcMinorProjectSetup()
         buildFile << """
+            import org.opensearch.gradle.JavaPackageType
+
             apply plugin: 'opensearch.internal-distribution-download'
 
             opensearch_distributions {
@@ -130,7 +132,7 @@ class InternalDistributionDownloadPluginFuncTest extends AbstractGradleFuncTest
                   type = "archive"
                   platform = "linux"
                   architecture = Architecture.current();
-                  bundledJdk = false
+                  bundledJdk = JavaPackageType.NONE
               }
             }
             tasks.register("createExtractedTestDistro") {
diff --git a/buildSrc/src/integTest/resources/org/opensearch/gradle/internal/fake_git/remote/distribution/archives/build.gradle b/buildSrc/src/integTest/resources/org/opensearch/gradle/internal/fake_git/remote/distribution/archives/build.gradle
index fbd5936061779..355b26ecced8c 100644
--- a/buildSrc/src/integTest/resources/org/opensearch/gradle/internal/fake_git/remote/distribution/archives/build.gradle
+++ b/buildSrc/src/integTest/resources/org/opensearch/gradle/internal/fake_git/remote/distribution/archives/build.gradle
@@ -32,7 +32,7 @@ subprojects {
     apply plugin:'base'
 
     tasks.register('tar', Tar) {
-        from('.')
+        from('build.gradle')
         destinationDirectory.set(file('build/distributions'))
         archiveBaseName.set("opensearch")
         archiveVersion.set("8.0.1-SNAPSHOT")
diff --git a/buildSrc/src/testKit/testingConventions/build.gradle b/buildSrc/src/testKit/testingConventions/build.gradle
index 676960bcc8b70..afd3f06a4ed68 100644
--- a/buildSrc/src/testKit/testingConventions/build.gradle
+++ b/buildSrc/src/testKit/testingConventions/build.gradle
@@ -21,7 +21,7 @@ allprojects {
     mavenCentral()
   }
   dependencies {
-    testImplementation "junit:junit:4.13.2"
+    testImplementation "junit:junit:${versions.junit}"
   }
 
   ext.licenseFile = file("$buildDir/dummy/license")
diff --git a/gradle/libs.versions.toml b/gradle/libs.versions.toml
index e5caa7cb23666..98bdccdc47a62 100644
--- a/gradle/libs.versions.toml
+++ b/gradle/libs.versions.toml
@@ -74,6 +74,7 @@ password4j        = "1.8.3"
 # test dependencies
 randomizedrunner  = "2.7.1"
 junit             = "4.13.2"
+junit5            = "6.0.0"
 hamcrest          = "2.1"
 mockito           = "5.16.1"
 objenesis         = "3.3"
diff --git a/plugins/identity-shiro/build.gradle b/plugins/identity-shiro/build.gradle
index 6479e1300be15..581cf89023883 100644
--- a/plugins/identity-shiro/build.gradle
+++ b/plugins/identity-shiro/build.gradle
@@ -33,7 +33,7 @@ dependencies {
   testImplementation project(path: ':modules:transport-netty4') // for http
   testImplementation "org.mockito:mockito-core:${versions.mockito}"
   testImplementation project(path: ':client:rest-high-level')
-  testImplementation 'junit:junit:4.13.2'
+  testImplementation "junit:junit:${versions.junit}"
 }
 
 /*